Biomedical subjects

M Winnemöller

Publications and source records attributed to M Winnemöller.

3 recordsLinked to original sources

PubMed1992

Partially phosphorylated glycogen phosphorylase in the lugworm Arenicola marina, its regulatory function during hypoxia.

Glycogen phosphorylase (GPase) from the body wall of the lugworm Arenicola marina (Annelida, Polychaeta) probably exists as a phospho-dephospho hybrid (GPase ab). The hybrid was identified by phosphorylation of purified lugworm GPase b (unphosphorylated form) with rabbit muscle GPase kinase and [gamma-32P]ATP. The completeness of phosphorylation was checked on DEAE-Sephacel. Only one GPase form was eluted. Its 32P incorporation was determined to 0.52 +/- 0.08 mol 32P/100,000 x g protein (n = 4). This GPase ab produced by in vitro phosphorylation has shown similar dependences on AMP and caffeine as GPase extracted from the body wall of the lugworm. Its reversible conversion with endogenous phosphatase and kinase to GPase b has also been demonstrated while a completely phosphorylated form (GPase a) was not detected neither in vivo nor in vitro. Lugworm GPase ab has shown a 2.4-fold higher specific activity as GPase b. The Km for P(i) was 16 mmol/l in absence and 13 mmol/l in presence of AMP. Half maximum activation by AMP was reached at 9 mumol/l. IMP up to 10 mmol/l did not activate and ATP up to 4 mmol/l did not inhibit GPase ab in absence of AMP.

Adenosine Monophosphate↗

PubMed1992

Interactions between thrombospondin and the small proteoglycan decorin: interference with cell attachment.

Decorin, a ubiquitous small interstitial dermatan sulfate proteoglycan, interacts with several extracellular matrix components, e.g., with type I collagen and fibronectin. Using a solid phase assay it is shown that the intact proteoglycan as well as its glycosaminoglycan-free core protein exhibits with KD values of about 5 nM and 2 nM, respectively, high affinity binding also to thrombospondin. However, the polysaccharide chain was required for an interaction with Sepharose-bound thrombospondin and served itself as ligand. In light of the results of binding studies with an N-terminal heparin-binding fragment of thrombospondin it is concluded that several structural features of thrombospondin and of decorin contribute to the mutual interaction of the two macromolecules. Thrombospondin substrata allowed attachment but prevented spreading of human skin fibroblasts. The addition of decorin or of its glycosaminoglycan-free core protein led to a considerable delay of cell attachment on a thrombospondin substrate. The strength of cell attachment appeared to be reduced. These data support the antiadhesive role of decorin regardless of whether subsequent cell spreading is supported or not.

Binding Sites↗

PubMed1991

Influence of decorin on fibroblast adhesion to fibronectin.

Decorin is a ubiquitous small dermatan sulfate proteoglycan carrying a single glycosaminoglycan chain. It is known for its ability to bind, via its core protein, to interstitial collagens. Decorin was purified from the secretions of cultured human skin fibroblasts under non-denaturing conditions. The intact proteoglycan and its glycosaminoglycan-free core protein were tested for their interference with fibroblast adhesion to a fibronectin substrate. Concentrations of 40 nmoles or more of hexuronic acid/ml of decorin or equivalent amounts of core protein inhibited cell adhesion. Inhibition was caused by an interaction of core protein with fibronectin and not by masking of the fibronectin receptor. When cell-binding fragments of fibronectin were used as substrates, a similar inhibition of cell adhesion by decorin core protein was found, and in vitro assays demonstrated an interaction of core protein with the cell-binding domain of fibronectin. Decorin core protein also inhibited the low degree of cell adhesion to heparin-binding fragments on the N-terminus and near the C-terminus of the fibronectin molecules.

Cell Adhesion↗